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羊水的动力学一、羊水的形成与代谢由于羊膜与绒毛膜均为部分性半透膜,细胞之间有通道,所以在早孕期母血清内之水分及小分子物质均可透析入羊膜腔,同样也有少部分水分及小分子物质来自胎儿毛细血管经薄层皮肤透入者,直至24孕周皮肤细胞角化为止。此时羊水无色澄清。12孕周后胎尿形成,直接排入羊水中。因胎尿是低渗的,所以随着孕周的增长,胎尿排出的增多,羊水的渗透压亦下降。再随着孕周的增长呼吸道的上皮及分泌物,皮肤脱落细胞及胎脂等均进入羊水中,羊水则逐渐变为混浊液。羊水与母血清及胎儿三者间之液体不断进行着快速的交换,每三小时羊水即可交换一次。足月时母体与胎儿间水分主要通过胎盘交换,每小时可达3600ml左右,通过胎膜母血与羊水交换量为400ml/小时左右。胎尿每24小时可排出600～800ml,而胎儿每天
Amniotic fluid dynamics First, the formation of amniotic fluid and metabolism As the amniotic membrane and chorionic membrane are partially semipermeable membrane, there are channels between cells, so in the first trimester maternal serum water and small molecules can dialysis into the amniotic cavity, There are also a small portion of water and small molecules from fetal capillaries through the thin layer of skin penetration, until 24 weeks of skin cells until the skin cells. Amniotic fluid at this time colorless and clear. 12 gestational weeks after the formation of fetal urine, directly into the amniotic fluid. Because of the low permeability of fetal urine, so with the growth of gestational age, increased discharge of fetal urine, amniotic fluid osmotic pressure also declined. And then with the growth of gestational age, respiratory epithelium and secretions, skin exfoliated cells and fetal fat into the amniotic fluid, amniotic fluid gradually become turbid liquid. Amniotic fluid and maternal serum and fetal fluid between the three ongoing rapid exchange of amniotic fluid every three hours to be exchanged once. Full-term when the water between the mother and fetus through the placental exchange, up to 3600ml per hour, through the fetal blood and amniotic fluid exchange amount of 400ml / hour. Tire urine can be discharged every 24 hours 600 ~ 800ml, while the fetus every day